SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b53714cf6008489250e655b13f3697acaf440147da186786cf34a314330286be' 
  AND token = 'p82mX9sbwtlpSiL6Tz7qA2x9Pd+fEt1exTPGwq7XvGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}